The Value Of A Replenished Quart>?

[ULVER]

I read a study somewhere, where testing was done concerning Mobil 1. They wanted to see how long they could run the oil, till it did not offer adequate protection. Seems the vehicle was using a quart every X about of miles. Anyway, it seemed that replenishing a quart really gave a boost to the used oil, allowing them to run the original host oil, to like 16K or something close.

I burn a quart pretty quickly in my Crown Victoria, though she runs like a top. With a quality synthetic, I was wondering if I were to replace a quart fairly often, if I could maybe go 10 or 12K (basically for me a year).

Does replaces a quart of quality oil, really pep the original fill that much? Thanks for thoughts...

 

[RedWolf4000]

ULVER, even if your Crown Vic did not burn oil, your vehicle could run oil change intervals between 10-12k with a quaity synthetic. Mobil 1 can achieve this with its M1 EP. Amsoil could also easily do the job.

If you add a quart every say 500-1000miles, I would think you could run the oil a looooong time considering every 5000 miles your actually doing an oil change. If your top-off exceeds your engine oil capacity its basically like your changing your oil, know what I mean?

I'm not reccommending this though, I'm just saying in theory you could probablly get away with this. (We have seen tests that show this is not as effective as a true drain of course)

Long story short, with top-ups you can be rest assured that you can change your Mobil 1 Extended Performance every 15k. Remember that Mobil is asking you to run it 15k, right on the bottle. (As long as your not racing or driving offroad) Mobil also has a warrantee you can print on there site that protects you from any damage that there 15k claim might cause. If a company is willing to do this then you should be assured without UOA's that the oil can go the year. Im sure amsoil could do this and more as well.

 

[C4Dave]

Isn't this why Amsoil recommends replacing the oil filter every 5000 miles? Not because the filter media is full of debris, but to get some more oil in there?

 

[deepsquat]

UMMMM I would never run 15000 miles without doing Used oil analysis along the way ..we haven't seen a lot of cars in the UAO section pot up ## good enough for people to be shouting "hey why aren't you going 15000 miles?" maybe les then a hand full of vehicles...my altima ..and an Accord that is ran 1000 miles a week
If you are burning oil ..then by-products ( pollutants) are being thrown off into your oil ..a top notch engine running 15000 with M1 ..no problem ..a crown Vic with bad rings ...no way

 

[Islandvic]

I was actually thinking this the other day.

My '96 Vic burns 1 qt evert 1000-1200 miles.

With a 6000 mile OCI, that's 5 quarts that have been replaced in the original 5 qt sump.

Math whizes, After 6000 miles, what would be the ratio of orig, 1st, 2nd, 3rd, 4th and 5th quarts of refill oil in the sump when I drain?

 

[AstroVic]

Each time you add a quart, you're reducing the amount of the original oil by 20%, so....

First quart: 80% original oil remains

Second quart: 64% original oil remains

Third quart: 51.2% original oil remains

Fourth quart: 40.96% original oil remains

Fifth quart: 32.768% original oil remains

Sixth quart: 26.2144% original oil remains

So, it's not like you're performing a complete oil change just by adding a quart five or six times in thousand-mile increments. There will ALWAYS be some amount of the original oil in the sump until you drain it completely.

 

[XS650]

quote:

---

Originally posted by Islandvic:
I was actually thinking this the other day.

My '96 Vic burns 1 qt every 1000-1200 miles.

With a 6000 mile OCI, that's 5 quarts that have been replaced in the original 5 qt sump.

Math whizes, After 6000 miles, what would be the ratio of orig, 1st, 2nd, 3rd, 4th and 5th quarts of refill oil in the sump when I drain?

---

Assuming you add a qt every 1000 miles.

Each time you get down to 4 qts and add a qt, you will have 80% old, 20% new oil. I other words you will replace 20% of what's in the sump each time.

original oil"

add a qt at 1000 miles = 80% of original oil = 4 qts
" 2000 miles = 64% of original = 3.2 qts
" 3000 miles = 51.2% = 2.56 qts
" 4000 miles = 40.96% = 2.05 qts
" 5000 miles = 32.77% = 1.64 qts

Ratios at 6000 miles are the same as at 5000 miles because you don't add any oil at 6000 miles

At 5,000 miles There will be 1 x 0.8^4 = 0.41 qts of the 1000 mile qt left

1 x 0.8^3 = 0.512 qts of the 2000 mile qt left

1 x 0.8^2 = 0.64 qts of the 3000 mile qt left

1 x 0.8 = 0.8 qts of the 4000 mile qt left

1 qt if new oil.

For a sanity check thats:

1.64 + 0.41 + 0.512 + 0.64 + 0.8 + 1 = 5.002 qts

"Oil burning engines, they're not a bug, they're a feature.

Bill Gates."


Average age of oil at 5,000 miles:

code:

---

1.64 x 5000 = 8200

0.41 x 4000 = 1640

0.51 x 3000 = 1530

0.64 x 2000 = 1260

0.80 x 1000 = 800

+ 1.00 x 0 = 0

----

13450 qt miles

---

13450 qt miles/5 qts = 2690 miles

At 6,000 miles be0pre adding another qt, the average age would be 3689 miles, after adding a qt it would drop back to:

code:

---

3689 x 4 = 14756

+ 0 x 1 = 0

--------

14756



14756/5 = 2951 miles

---

A few comments:

Someone please check my arithmetic.

The calculation can be done much more elegantly but that wouldn't illustrate what's happening to your individual quarts of oil as clearly as this way does.

The increase in average oil age is tending towards alimit, probably less than 4,000 miles even if you drive a bazillion miles without changing your oil.

If you just look at the average oil age numbers, it looks like you could run forever by replacing 1 qt of burned oil evry thousand miles. The problem is that the same engine conditions that cause the oil to be burned usually muck up the oil faster than normal.

OTOH, if you were losing the oil though leaks, you could just keep adding oil and have resonably fresh oil in your engine forever. You could also make some money on the side by getting a contract from the county to oil their back roads

 

[Bill]

quote:

---

posted by C4Dave

Isn't this why Amsoil recommends replacing the oil filter every 5000 miles? Not because the filter media is full of debris, but to get some more oil in there?

---

Amsoil recommends replacing the oil filter every 6 months or 12500 miles which ever comes first

 

[JohnBrowning]

In heavy commercial diesels you always adjust oil change interval to take oil consuption into account. You push out the oil change the more oil that engine consu,es.

 

[johnd]

I had a '86 VW rabbit what had bad valve stem seals and used a half quart of oil every 10 gal. of gas. As I was a quart every 400 mi, it never even got dirty. I finally just started changing the filter every 3000mi and didn't ever drain the oil. I finally got the seals replaced and went back to the normal routine after 3-4 years. That car had 300K+ on it when I sold it and was still running well and still not using any oil.

 

[LVHospiceRN]

quote:

---

Originally posted by deepsquat:
UMMMM I would never run 15000 miles without doing Used oil analysis along the way ..

---

and if you are going to do a UOA, why not just change the oil out instead? A UOA with TPN is what $30 or so now? $30 gets me five quarts of German Castrol and a Mobil 1 filter....I KNOW they numbers are good then...

I understand that you "save resources" if you do an UOA and extend the drain time...but other than that, what is the benefit?

Just IMHO, YMMV
darrell
sin city

 

[Islandvic]

My thoughts were that if by the 5000 mile mile mark, I would have only 1/3 of the original oil left.

2/3 of the oil would be newer.

At 6000 miles, I have 80% of the last quart with only 1000 miles on it left, and 54% of the next to the last quart left with only 2000 miles on it.

Could I push the OCI out some b/c of the math?

 

[White 03]

If the oil is lost because of normal usage is the oil lost compleat or is the good stuff in oil lost leaving the bad things, like soot or dirt?

I can see if a quart was drained or the filter changed that oil would be like the rest of the oil and a quart of good things along with the bad things would come out. But with normal usage does the volatile parts burn off and leave the contaminantes?

I suppose leakage would be like draining.

 

[methusaleh]

I first thought the original post was asking how long a given quantity of oil could last before its lubricating qualities diminished. Then we have all this talk about losing oil from an engine and needing to top off...I looked back and yes indeed that was the original poster's concern.

What about how long a crankcase full of M1 that is *NOT* topped off/not losing oil will "last"?

Reason I ask is because I read this thread with great interest. Being one who runs M1 (50/50 with Chevron Supreme dino) and remembering what my high school shop teacher told us 20 years ago ("oil can get TIRED, but it never really WEARS OUT"), I was very interested to see if anyone had a definitive answer to what I thought was the original question...

 

[Islandvic]

methusaleh, ulver wanted to know when he adds a quart to his Vic, does the added qt help the old oil in terms of its ability for the oil do do its job correctly.

Does 4 old qts + 1 new qt = better than 5 old qts?

This is how I read it.

Me and Ulver asked by doing this, can we push our OCI out longer.

 

[methusaleh]

Yeah, I hear you, but I am saying that it makes me wonder just how long a given quantity of oil will last, if you will, without topping it off, without any leaks, etc.

As in, I change my oil and put 5.5 quarts in. Without that quantity being added to, and no known leaks or oil burning, how long will that quantity of oil last before it is too "tired" to do much anymore.

 

[Islandvic]

Methusaleh, you can determine how "tired" your oil is by an Used Oil Analysis, aka UOA.

There is a section on the forum devoted to people's UOA's.

How long it will last has to do with driving conditions, type/brand of oil, and the vehicle.

Do you run 50/50 blend of M1 and Chevron dino to save $$$, or to use up your stash?

 

[methusaleh]

Thanks Islandvic, yes I have seen the UOAs just wasn't sure if there was a definitive "answer" to my question.

I've always run a combo of synth/dino because I was taught that by my uncle, a sort of "get the best of both worlds" philosophy I believe. The more I read on this site, the more I feel it was sage advice, but I just invested in a case of the new M1 formula so I will be using just that for a while. I have varied brands for the dino oil, but just happened to be lucky enough to get a bunch of Chevron stuff at Wally World on clearance. My next "cocktail" move will definitely include an additive.